France and the three Benelux countries on Thursday launched a plan to offer EU funds to African countries in return for help stemming the flow of migrants to Europe.

With the issue of immigration fuelling populist movements across Europe, the EU is under pressure to come up with ways to stop the arrival of illegal migrants, many of whom risk their lives trying to cross the Mediterranean in rickety boats.

French President Emmanuel Macron and the prime ministers of Belgium, Luxembourg and the Netherlands said they had agreed on "concrete" proposals to put forward at a meeting of EU leaders in Salzburg, Austria, later this month.

Dutch PM Mark Rutte said that "agreements like those concluded with Turkey" were needed to build on a hard-fought but vague deal on migration thrashed out at an EU summit in June.

The EU struck a deal with Turkey in 2016 in a effort to stem the flow of migrants, under which Ankara agreed to take back illegal migrants landing on Greek islands in exchange for incentives including financial aid.

Over the last year the bloc has been stepping up its efforts to support African countries with aid and investment in a bid to reduce the incentives for people to leave their home countries to seek a better life in Europe.

"The European Union must deploy a form of Marshall Plan for Africa, with a concrete operational ambition with African partners", said Belgian Prime Minister Charles Michel.

The four leaders also urged more help for European countries of first arrival, Italy and Spain, to deal with the arrivals, but all maintain that these countries must have responsibility for arrivals -- a major point of contention with Italy.

The hardline anti-migrant government in Rome has demanded the EU rotate the ports where migrants rescued in the Mediterranean disembark, arguing that Italy was shouldering an unfair burden.

Italy has been turning away ships with migrants rescued at sea in a campaign to force other EU countries to take them, and last month it threatened to block the EU budget over the issue.

Macron said the countries of arrival "have a responsibility and they cannot get rid of it, but there must be financial solidarity".

"We have made progress today and together we will bring concrete solutions to the Salzburg summit," he added.